The present invention relates to a packaging machine and to a method for producing packages made of a film.
In packaging machines and in particular in the forming and sealing stations of the packaging machine, pressure must be provided for the heating of the film, the forming of the film and the sealing of the package. In conventional systems, the pressure is hereby controlled via manually settable filling times or manual pressure controllers, that is, a certain pressure is generated for a predetermined period of time via the opening of a valve. The pressure is thereby subject to fluctuations and a reproducibility is not given. This is disadvantageous in particular because different types of packaging and films in a packaging machine require different settings so that the reproducibility is important.
Furthermore, the valves comprising manual pressure controllers previously used for the gassing of packages require a backpressure, which often builds up too late for a rapid control process, in particular with small chambers and which thus causes the package to inflate.
The use of proportional controllers, which comprise a measuring and control engineering, is not common in packaging machines, because they increase the pressure too slowly. Conventional proportional controllers cannot completely open the valve in particular at the onset of the control, because there is a risk of increasing the pressure too much. They are thus too slow. Material stress limits can furthermore be exceeded.